Galloper Wind Farm Project - Galloper Wind Farm proposal

Galloper Wind Farm Project 

Preliminary Environmental Report - Chapter 13: Marine and 

Intertidal Ecology

Document title Galloper Wind Farm Project 

Preliminary Environmental Report - Chapter 

13: Marine and Intertidal Ecology 

Document short title Galloper Wind Farm PER 

Status Final Report 

Date 3 June 2011 

Project name Galloper Wind Farm Project 

Client Galloper Wind Farm Limited 

Royal Haskoning Reference 9V3083/R01/303972/PBor 

Drafted by Peter Gaches, Jon Allen et al. 

Checked by Rob Staniland, Peter Thornton 

Date/initials check RS PT 30.05.2011 

Approved by Dr. Martin Budd (Royal Haskoning) 

Date/initials approval MB 30.05.2011 

GWFL Approved by Kate Tibble 

Date/initials approval KT 1.06.2011 

Galloper Wind Farm PER 9V3083/R01/303972/PBor 

Final Report - i - 3 June 2011

CONTENTS 

Page 

13 MARINE AND INTERTIDAL ECOLOGY 1 

13.1 Introduction 1 

13.2 Guidance and Consultation 1 

13.3 Methodology 3 

13.4 Existing Environment 11 

13.5 Assessment of Impacts - Worst Case Definition 34 

13.6 Assessment of Impacts during Construction 37 

13.7 Assessment of Impacts during Operation 47 

13.8 Impacts during Decommissioning 51 

13.9 Inter-relationships 51 

13.10 Cumulative Impacts 52 

13.11 Outline Monitoring 55 

13.12 Summary 56 

13.13 References 59 


Final Report - i - 3 June 2011

13 MARINE AND INTERTIDAL ECOLOGY 

13.1 Introduction 

13.1.1 This Chapter of the Preliminary Environmental Report (PER) describes the 

benthic (marine and intertidal) biological resource within the Galloper Wind 

Farm (GWF) site as well as the wider area of the Outer Thames Estuary and 

southern North Sea. 

13.1.2 This Chapter serves to characterise the distribution and abundance of 

benthic species known to occur within both the study area and across the 

wider region through site specific or regional surveys. Subsequent to this, it 

then presents the findings of the assessment of potential impacts of the 

construction, operation and decommissioning phases of the GWF project and 

provides detail on the proposed approach to mitigation of these impacts. 

13.1.3 This Chapter covers effects on the habitats below mean high water springs 

(MHWS). Effects on terrestrial habitats above MHWS are presented in 

Chapter 24 Terrestrial Ecology. Impacts on the fisheries resource are 

described separately in Chapter 14 Fish and Shellfish Resource. 

13.2 Guidance and Consultation 

Policy and guidance 

13.2.1 The following paragraphs provide detail from the Revised Draft National 

Policy Statement (NPS) for Renewable Energy Infrastructure (EN-3), which 

contains specific requirements for assessment of impacts on the subtidal and 

intertidal zones. Included within the stated specific requirements are 

references to the relevant section of this Chapter, where the concern has 

been addressed. 

13.2.2 In relation to the intertidal, Section 2.6.81 of NPS EN-3 (Department for 

Energy and Climate Change (DECC), 2009) details that where necessary an 

assessment of the effects of installing cable across the intertidal zone should 

include information about: 

� Potential loss of habitat (Section 13.5); 

� Disturbance during cable installation and removal (decommissioning) 

(Sections 13.5 and 13.7); 

� Increased suspended sediment loads in the intertidal zone during 

installation (Section 13.5); and 

� Reduced rates at which the intertidal zone might recover from 

temporary effects (Section 13.5). 

13.2.3 Section 2.6.113 of NPS EN-3 identifies the key considerations with regard to 

the subtidal environment and states that where relevant the assessment 

should include: 


Final Report Chapter 13 – Page 1 3 June 2011

� Loss of habitat due to foundation type including associated seabed 

preparation, predicted scour, scour protection and altered sedimentary 

processes (Section 13.5 and 13.6); 

� Environmental appraisal of intra-array, inter and intra-array and export 

cable routes and installation methods (Section 13.5); 

� Habitat disturbance from construction vessels extendible legs and 

anchors (Section 13.5); 

� Increased suspended sediment loads during construction (Section 

13.5); and 

� Predicted rates at which the subtidal zone might recover from 

temporary effects (Section 13.5). 

13.2.4 In addition, this assessment has been undertaken with due consideration of 

the following legislation and guidance (and amendments, where appropriate): 

� Draft guidelines for data acquisition to support marine environmental 

assessments for offshore renewable energy projects (Centre for 

Environment Fisheries and Aquaculture Science (Cefas), 2011); 

� Guidance on the Assessment of Effects on the Environment and 

Cultural Heritage from Marine Renewable Developments (draft). 

Produced by: the Marine Management Organisation (MMO), the Joint 

Nature Conservation Committee (JNCC), Natural England, 

Countryside Council for Wales (CCW) and Cefas, December 2010; 

and 

� Guidelines for ecological impact assessment in Britain and Ireland. 

Marine and Coastal, Final Document (Institute of Ecology and 

Environmental Management (IEEM) 2010). 

Consultation 

13.2.5 The following paragraphs and Table 13.1 provide a summary of the 

consultation with regard to marine ecology that has taken place at key 

junctures throughout the planning phase of the project. Furthermore, an 

indication of where the relevant consultee concern has been addressed 

within this Chapter is also provided. 

13.2.6 Galloper Wind Farm Limited (GWFL) undertook early consultation with the 

JNCC, Natural England, the Marine and Fisheries Agency (MFA) (now the 

MMO) and Cefas on the requirement for, and scope of, site specific surveys 

to characterise the benthic environment. Furthermore, representatives of 

Cefas and JNCC were invited to be present during the data interpretation 

phase of the site surveys to ensure the work was carried out in accordance 

with the Scope of Works. 

13.2.7 Subsequent consultation on the predicted impacts on the marine and 

intertidal ecology and approach to their assessment took place through the 

formal request for a Scoping Opinion from the Infrastructure Planning 

Commission (IPC). 



Table 13.1 Summary of consultation on marine ecology issues 

Date Consultee Summary of comment Section where 

addressed 

July and 

August 

2009 

JNCC/Natural 

England/ 

MFA/Cefas 

Aug 2010 JNCC/Natural 

England (through 

Scoping Opinion) 

Aug 2010 JNCC/Natural 

England (through 

Scoping Opinion) 

13.3 Methodology 

Confirmed requirement for and 

scope of benthic survey 

In recognition of presence of 

Sabellaria spinulosa, Annex I 

surveys will be required prior to 

construction 

Discussion of potential alteration 

of habitat due to compaction of 

sediment 

Study area 

13.3.1 The study area with regard to marine and intertidal ecology encompassed the 

GWF site, export cable corridor and surrounding seabed within a single tidal 

excursion (i.e. the net horizontal extent of one tidal cycle) (Figure 13.1a and 

13.1b). The intertidal study area extended from mean low water springs 

(MLWS) to MHWS, for approximately 500m either side of the proposed 

landfall at Sizewell (adjacent to Sizewell Hall to the south, and the end of 

Sizewell Gap road to the north) (Figure 13.2). 

Characterisation of existing environment 

13.3.2 There are an extensive number of existing studies that cover the area, which 

enable a detailed broadscale characterisation of the benthic resource within 

the wider study area. A number of these studies encompass the GWF study 

area and therefore augment the level of site specific knowledge. Those 

existing studies that are considered of relevance to the GWF project include: 

� Environmental Statement’s (ES’s) from other offshore wind farm 

developments within the Outer Thames Strategic Area (GE Wind 

Energy, 2002; Greater Gabbard Offshore Winds Limited (GGOWL), 

2005; Global Renewable Energy Partners (GREP), 2002; London 

Array Ltd (LAL), 2005); 


Final Report Chapter 13 – Page 3 3 June 2011 

13.4 

13.4 

13.5 

� A broadscale survey conducted by Cefas as part of national 

monitoring programmes (Cefas, 1997);

� Investigative surveys 1 by the conservation agencies (JNCC and 

Natural England) as part of the Natura 2000 site selection process; 

and 

� The Outer Thames Estuary Regional Environmental Characterisation 

(Marine Aggregate Levy Sustainability Fund (MALSF), 2009). 

13.3.3 These data were used to provide background for the area and support for 

site specific survey conducted specifically for the GWF Environmental Impact 

Assessment (EIA). 

13.3.4 A site specific survey was undertaken for the study area associated with the 

GWF site and the export cable corridor. The methodologies for this survey 

are summarised in the following paragraphs (a full description will be 

provided within the subsequent ES). The survey methodologies were agreed 

with the relevant agencies (Cefas, JNCC and Natural England). 

13.3.5 No dedicated intertidal survey was undertaken as the area of landfall and 

surrounding environs have been surveyed in detail as part of the Greater 

Gabbard Offshore Wind Farm (GGOWF) consent studies and the results are 

considered to remain valid. The habitats of the intertidal are predominantly 

barren shingle and ephemeral seaweeds (see 13.4.4) and are not considered 

sensitive or likely to have changed since the characterisation surveys of 

2005. This approach was clearly set out in the Scoping Report (SSER and 

RWE NRL, 2010) and received no objection from the consultees. 

GWF Survey strategy 

13.3.6 The GWF benthic survey campaign was undertaken in accordance with 

Cefas guidance (Cefas, 2004). The work comprised the use of a 

combination of benthic grab, drop-down camera and epibenthic beam trawl 

sampling in order to fully characterise the benthic infaunal and epifaunal 

communities. 

13.3.7 The grab and camera drop sampling locations were based around a predetermined 

grid that was informed by the knowledge gained from existing 

studies that covered the GWF study area (namely GGOWL, 2005 and 

MALSF, 2009). The survey was designed to generate even coverage of the 

seabed across the study area. 

13.3.8 In addition to sample stations within the development footprint, near field 

comparison sampling stations were positioned outside the development area 

and control (reference) stations were located outside a tidal excursion south 

of the area and out of the path of tidal flow to the east (offshore). In total 97 

grab stations and 98 drop down camera stations were selected for sampling 

(see Figures 13.1a and 13.1b). 

1 http://www.naturalengland.org.uk/ourwork/marine/sacconsultation/default.aspx 



13.3.9 After the approximate location of each sample station was chosen, these 

locations were fine-tuned, as necessary, to ensure representative sampling 

of different habitats based on interpretation of the side scan sonar and 

multibeam data collected as part of the geophysical survey programme 

(Chapter 10 Physical Environment). 

13.3.10 The beam trawl surveys were carried out along sample lines perpendicular to 

the export cable corridor and were positioned to sample all of the benthic 

biotopes identified in the GGOWF EIA (GGOWL, 2005) in the adjacent cable 

corridor. Additional reference trawls were located to the north and south of 

the cable route (see Figures 13.1a and 13.1b). 

13.3.11 In addition, pre construction beam trawl surveys were carried out by Brown 

and May in autumn/winter 2008 (Brown and May Marine Ltd, 2009a) and 

spring 2009 (Brown and May Marine Ltd, 2009b) in order to characterise the 

fisheries resource of GGOWF. The results of these surveys are described in 

full in Chapter 14 Fish and Shellfish Resource, but the epifaunal 

communities recorded are also described here. Figures 13.1a and 13.1b 

indicate the locations of the beam trawl surveys carried out. 

13.3.12 With the exception of the Brown and May survey, the surveys were carried 

out by CMACS Ltd, supported by Aquatech Ltd and Osiris Projects Ltd 

survey vessels in the autumn of 2009 from 19th September to 28th October 

and in the spring of 2010 from 1st March to 14th March. 

Subtidal benthic grab survey 

13.3.13 A total of 97 stations were selected for taking single grab samples for benthic 

invertebrate infauna and sediment analyses (Figure 13.1a and 13.1b). A 

mini Hamon grab (0.1m 2 sample area) was used to sample the seabed; this 

was an equivalent design to that used in the original GGOWF EIA, which 

therefore ensured continuity between the two projects and enabled 

comparison of the datasets. Samples were rejected if they were of less than 

5l (or 2.5l over hard-packed sands). Stations were only abandoned after 

three successive failures to obtain a sample. Grab samples were 

successfully obtained from 90 of the stations. Any stations that were 

abandoned were added to the stations to be visited with the drop down 

camera. 

13.3.14 The drop-down camera system utilised a freshwater housing unit, which 

permitted images to be obtained in low visibility/high turbidity environments. 

Still images were obtained at all 98 camera stations and at the seven failed 

grab stations. In addition, images were taken at four grab stations where 

there was considered to be potential for the presence of the Ross worm 

Sabellaria spinulosa based on the interpretation of the geophysical survey 

data (see Figure 10.1) or knowledge from the previous studies associated 

with the GGOWF project. S. spinulosa when occurring in reef form, serves 

as an important and sensitive habitat (as discussed in detail in Section 13.4). 

Consequently, the survey strategy was carefully adapted in accordance with 

guidance (e.g. Gubbay, 2007) and through consultations with the statutory 



nature conservation bodies to ensure that the appropriate techniques were 

utilised to ensure adequate characterisation with minimal damage to the 

feature. 

13.3.15 At stations where S. spinulosa aggregations were recorded, further 

photographs were taken between 20m and 40m north, south, east and west 

of the original location. If the species was observed in those images, a 

further four images were taken between 70m and 100m north, south, east 

and west of the original location. The aim was to estimate the spatial extent 

of aggregations when present. 

Subtidal epibenthic survey 

13.3.16 Three epibenthic surveys have been undertaken to characterise the existing 

environment; an autumn (October 2008) and spring (April 2009) (as part of 

wider surveys to characterise the fish and shellfish resource, see Chapter 

14), and by CMACS in the summer of 2009 as part of the benthic sampling 

campaign to ensure full coverage of the export cable corridor was achieved. 

13.3.17 All surveys were carried out using a standard Cefas-design 2m beam trawl 

with a 5mm square mesh cod-end insert and chain matrix between the beam 

and foot-rope. Trawling was undertaken for a period of 5 to 10 minutes over 

a distance of approximately 300m into the prevailing current with a speed of 

approximately 2 knots over the ground, in accordance with Boyd (2002). 

13.3.18 A digital photograph was taken of each trawl sample before any sorting or 

identification took place. Epibenthic invertebrates were counted and 

identified to species level where possible, with colonies of hydroids, soft 

corals and bryozoans being recorded as present or absent or recorded by 

weight. Any invertebrates not identified in the field were retained and 

preserved for future taxonomic identification. The samples collected during 

the trawls undertaken by Brown and May in 2008 and 2009, were sub 

sampled at sea for two of the trawls due to the large number of organisms 

caught (Brown and May Marine Ltd, 2009b). 

Analysis of benthic and epibenthic data 

13.3.19 Univariate analyses were conducted to characterise the benthos, this 

included determining the proportions of taxa recorded in the samples and 

undertaking diversity index analyses. In addition, the communities present 

were classified, where possible, in accordance with the Marine Habitat 

Classification for Britain and Ireland (version 04.05) (Connor et al., 2004). 




Final Report Chapter 13 - Page 7 3 June 2011



Intertidal surveys 

A number of Phase 1 habitat surveys have been undertaken in the area of 

the cable landfall for both the GGOWF and GWF projects. The reports, 

which have described some, or all of the relevant intertidal environment, are 

detailed in Table 13.2. These surveys, as well as the GGOWF ES, have 

been used to inform the characterisation of the intertidal environment at the 

cable landfall site at Sizewell. 

Table 13.2 Surveys describing the intertidal environment of the study area 

Survey Title Author Year Intertidal area 

surveyed 

Characterisation of intertidal and 

terrestrial ecology in relation to 

onshore works for the proposed 

GGOWF development 

Centre for Marine 

and Coastal 

Studies Ltd 

(CMACS) 

2005 Specific intertidal habitat 

survey completed 

GWF Phase 1 habitat survey Royal Haskoning 2009 Upper intertidal limit 

(beach/dune areas) – no 

specific intertidal survey 

GWF, Sizewell ecology survey report 

for GWFL 

The Ecological 

Consultancy 

2010 Upper intertidal limit 

(beach/dune areas) – no 

specific intertidal survey 

13.3.20 The coverage of these survey areas in relation to the GWF project study area 

are provided in Figure 13.2. 





Assessment of impacts 

13.3.21 Impacts associated with the construction, operation and decommissioning of 

GWF are assessed in accordance with the methodology detailed in Chapter 

5 EIA Process. The details provided in Chapter 6 Project Details have 

been used to establish a realistic worst case development scenario for the 

assessment of impact on marine and intertidal communities. 

13.3.22 The impact assessment has, and will continue to be informed by a number of 

dedicated studies, such as the numerical modelling undertaken to establish 

potential effects on the hydrodynamic and therefore, geomorphological 

regime (Chapter 10). Some of these studies are still ongoing and therefore 

the impact assessment will be reviewed and finalised once these studies are 

completed. The assessment of impacts presented within this PER have also 

been informed by studies associated with existing windfarms. Of particular 

relevance are the ongoing monitoring studies at the adjacent GGOWF project 

(GGOWL, 2005). 

13.3.23 Other chapters within this PER (such as Chapter 11 Marine Water and 

Sediment Quality) have been used to inform the assessment where interrelationships 

are relevant. 

13.4 Existing Environment 

Intertidal ecology 

13.4.1 The Suffolk coast in this area is comprised of sand dunes, with dune 

sequences including dune slacks and dune heathlands and coastal 

vegetated shingle. There are a number of designated sites to the north and 

south of the cable landfall which include these features, as detailed in 

Chapter 9 Nature Conservation Designations. 

13.4.2 Sizewell Beach is managed by Suffolk Wildlife Trust, although the study area 

has no statutory designation. The beach supports vegetated shingle habitat, 

which is a UK Biodiversity Action Plan (UKBAP) habitat and is rare and 

decreasing in Britain and Europe (GGOWL, 2005). Vegetated shingle 

beaches in Suffolk are known to support a range of plant species, including 

the nationally rare sea pea Lathyrus japonica and rare invertebrates 

associated with this habitat. Vegetated shingle habitat has been restored in 

front of Sizewell Power Station; natural examples are present towards 

Dunwich, Minsmere and Dingle (GGOWL, 2005). Habitats and species 

present above MHWS are considered as terrestrial and subsequently 

detailed and assessed within Chapter 24. 

13.4.3 The beach at Sizewell consists of an area of upper shore steep shingle 

backed by open dune habitat with a shallower gradient lower shore of sand 

with some overlying shingle. Landward of the beach lies a dynamic shingle 

ridge vegetated by patches of forbs and occasional clumps of marram grass 

(see Chapter 24, Section 24.4 for further detail). Sea kale Crambe maritima 

occurs abundantly in this landward zone right up to the high tide mark. There 



are also occasional small accumulations of decomposing fucoid seaweeds 

and dead wood along the strandline (CMACS, 2005). 

13.4.4 Below the MHWS the beach is of shingle and sand (The Ecology 

Consultancy, 2010, Royal Haskoning, 2009) (Figure 13.3). In terms of 

biotopes, the 2005 CMACS intertidal survey (see Table 13.2) identified 

barren littoral shingle (LS.LCS.Sh.BarSh) and barren littoral coarse sand 

(LS.Lsa.MoSa.BarSa) as the dominant communities of the upper and lower 

shore respectively within the survey area on Sizewell Beach. The only other 

intertidal biotope noted in the survey was ephemeral green or red seaweed 

(freshwater or sand influenced) (LR.FLR.Eph) which was present on five 

large concrete anchor blocks (Target Note 1 on Figure 13.4). In small areas 

of the upper shore shingle there were patches of barren sand 5 to 10m 2 in 

extent. These were classed as barren littoral coarse sand (Target Note 1 

and 2 on Figure 13.4). No macrofaunal life was noted in any intertidal 

biotope, and no biotopes or species of any sensitivity/value were identified. 

13.4.5 Although the detailed survey was completed in 2005, it is unlikely that the 

intertidal communities identified would have changed significantly in the 

intervening years. The community composition is determined by the shingle 

substrate which creates few opportunities for colonisation leading to 

depauperate numbers of individuals and species. For the purpose of the 

EIA, it is assumed that the intertidal ecology is as it was during the 2005 

survey. 







Subtidal ecology 

Infauna – regional context 

13.4.6 The benthic habitats of the southern North Sea are defined by the substrata 

of the seabed (Jones et al, 2004). Mobile sand dominated habitats are 

generally considered to be species poor and are characterised by robust 

species such as annelid worms and fast burrowing bivalves (Barne et al, 

1998, Jones et al, 2004). Epibenthic flora and fauna normally occur on 

mixed substrata with significant coarse components, where a range of microhabitats 

allow colonisation by a wide array of species (Jones et al, 2004). 

13.4.7 The GGOWF ES (GGOWL, 2005) summarised the work done to that date on 

the regional context of the offshore communities. Key studies used in the 

GGOWL (2005) assessment included Glamerec (1973), Kunitzer et al (1992), 

Frauenheim et al. (1989), together with site specific studies for other offshore 

wind farms Gunfleet Sands, Kentish Flats and London Array (GREP, 2002, 

GE Wind Energy, 2002, LAL 2005). These studies conclude that the offshore 

communities found in the Outer Thames Estuary region are very much 

dependent on the substrate with species composition varying from finer to 

coarse sediments. The MALSF Regional Environmental Classification (REC) 

work (MALSF, 2009) found four broad groups of benthic infauna across the 

region, dominated at the high level by sublittoral coarse sediment (SS.SCS) 

and sublittoral sands and muddy sand (SS.SSa) habitat complexes (Connor 

et al, 2004). 

13.4.8 Surveys for GGOWF identified the five most abundant taxa at the Greater 

Gabbard site, and areas immediately adjacent, as the Ross worm Sabellaria 

spinulosa, the barnacle Verruca stroemia, the porcelain crab Pisidia 

longicornis, the sea urchin Echinocyamus pusillus and the polycheate worm 

Lumbrineris gracilis (GGOWL, 2005). These species are patchily distributed 

throughout the site. 

13.4.9 The five main biotopes / communities recorded were as follows: 

� SS.SSA.IiSa.ImoSa Infralittoral mobile clean sand with sparse fauna; 

� SS.SCS.ICS.Glap Glycera lapidum in impoverished infralittoral mobile 

gravel and sand; 

� SS.SCS.CCS.MedLumVen Mediomastus fragilis, Lumbrineris spp. 

and venerid bivalves in circalittoral coarse sand or gravel; 

� SS.SBR.PoR.SspiMx Sabellaria spinulosa on stable circalittoral mixed 

sediment; and 

� Scalibregma (annelid worm) dominated sands / muddy sands. 

13.4.10 A common denominator of all of the biotopes / communities in the study area 

is that they are all adapted to surviving in turbid waters with very high levels 

of suspended sediments (GGOWL, 2005). 



13.4.11 The MALSF REC project identified two broad infaunal groups which were 

present across the GWF study area: Cluster B and Cluster C. Cluster B is 

associated with coarse mixed muddy, sandy gravels and gravelly sands. 

Species richness and diversity, together with biomass, were high in 

comparison to other sample clusters across the REC area (MALSF, 2009). 

Conspicuous species included the polychaetes, S. spinulosa, Lumbrineris 

gracilis, Notomastus spp., the amphipod Ampelisca spinipes, brittlestars 

Ophiuroidea and sea anemones Actiniaria. Biotopes associated with this 

cluster were; SS.SCS.CCS.MedLumVen, SS.SMu.ISaMu.AmpPlon, 

SS.SCS.CCS, CR.MCR.SfR and SS.SBR.PoR.SspiMx (MALSF, 2009). 

13.4.12 Cluster C was associated with comparatively clean sand and slightly gravelly 

sand sediments (MALSF, 2009). The associated macrofauna within each 

grab sample were sparse in comparison with the other faunal groupings and 

were characterised by a range of typical sand and gravelly sand species 

such as the polychaetes Nephtys cirrosa, Ophelia borealis and Glycera 

oxycephala, the amphipods Bathyporeia elegans and Urothoe brevicornis, 

the mysid shrimp Gastrosaccus spinifer and Ophiuriodea (MALSF, 2009). 

Biotopes associated with this cluster were SS.SSa.IFiSa.MoSa and 

SS.SSa.IFiSa.NcirBat (MALSF, 2009). 

13.4.13 Dense aggregations of the S.spinulosa have been found in the deeper, 

polychaete dominated areas, on mixed sediments across the GWF study 

area (MALSF, 2009). S. spinulosa is a common species which often forms 

“crusts”, which in many cases are temporary features that break up in 

autumn/winter storms (Gubbay, 2007 and Limpenny et al, 2010). The 

species can also occur in reef form, at which point it is considered of high 

ecological importance, further discussion on this is provided in Sections 

13.4.56-60 

13.4.14 Interpretation of sidescan surveys to summarise major seabed features for 

GGOWF (GGOWL 2005) found no indications of extensive reef like 

structures, and suggested most of the area away from the Gabbard and 

Galloper sandbanks to be generally thin layers of sand and gravel over clay. 

The ES for GGOWF therefore concluded that given the evidence it was 

unlikely that there were areas of substantial S. spinulosa communities within 

the site although it could not be ruled out. However, it should be noted that 

the sidescan did not extend all the way to the south east corner of the 

proposed GWF development area. 

13.4.15 The only Sabellaria reefs found by the MALSF REC surveys were well to the 

south of GGOWF and GWF in the vicinity of Long Sand Head approximately 

20km to the south of the GWF boundary (MALSF, 2009). 



Results of GWF surveys 

Infauna 

Univariate analysis of infauna 

13.4.16 The infaunal analysis of the GWF survey was based on 90 Hamon grab 

samples of 0.1m 2 each. From the samples analysed, a total of 6,052 

individuals from 265 taxa were identified, the majority to genus or species 

level but some only identifiable to higher taxonomic levels (e.g. to phylum) 

(CMACS, 2010). The greatest numbers of taxa in any one sample was 63 at 

Station G78 to the northwest of the Galloper Bank, between the existing 

GGOWF inter array cable route and the proposed GWF inter array cable 

route (Figure 13.5). Figures 13.5 to 13.7 (see Pages 21, 22, and 23) 

indicate the number of species, abundance and diversity of the benthic 

samples both in the wind farm area and along the export cable corridor. 

Plots 13.1 and 13.2 show, as a percentage, the numbers of taxa and the 

number of individuals within the major groups present in the infauna. 

Plot 13.1 Numbers of taxa of the major groups present in infauna 

Bryzoa 9% 

Ecinodermata 3% 

Mollusca 14% 

Source CMACS (2010) 

Cnidaria 6% 

Others 5% 

Crustacea 20% 

Annelida 43% 

13.4.17 The greatest number of individuals found in a grab sample was 476 at 

Station G51 to the east of Area B (Figure 13.5). Samples from deeper water 

areas generally had more individuals than shallower sites, although not all 

deep water samples contained high numbers of invertebrates. Similarly, 

although not always the case, coarser sediments seemed to support higher 

numbers of invertebrates (especially well illustrated along the export cable 

route and when comparing the western and eastern sections of Area A). 



Overall there were relatively few individuals recorded per sample across the 

site. 

13.4.18 There were markedly fewer individuals to the east of the Inner Gabbard Bank 

and on the inter and intra-array and export cable routes. The exception to this 

trend was Station G51 (on the southeastern edge of Area B), although this 

location was dominated by a large number of a single species (S. spinulosa). 

Plot 13.2 Numbers of individuals by major groups present in infauna 

Source CMACS (2010) 

Ecinodermata 

8% 

Mollusca 

12% 

Cnidaria 

2% 

Crustacea 

11% 

Others 

8% 

Annelida 

59% 

13.4.19 The dominant faunal group across the survey site were annelid worms, which 

comprised just under half of the total number of taxa, and just over half of the 

total number of individuals recorded (Plots 13.1 and 13.2, see above). 

Crustaceans and molluscs were the next most commonly recorded groups, 

both in terms of taxa and individuals. 

13.4.20 Only a very limited number of the faunal samples were not dominated by 

annelids and this accords with the results of sampling at both the GGOWF 

and London Array wind farms (CMACS, 2005a, 2005b). 

13.4.21 As would be expected, given the previously described predominance of 

annelid taxa, the most abundant species across the survey site were also 

annelids, with six of the twelve most abundant species belonging to the 

group. The most common species from the samples was the keelworm 

Pomatoceros triqueter with a total of 807 individuals recorded. This species 

is sessile, occupying a calcified tube which encrusts the surface of gravels, 

and shells. This species was well distributed across the survey area, being 

found at a total of 37 stations, but was particularly abundant at stations G51 

and CG12. 



13.4.22 Shannon Wiener’s diversity index 2 is displayed for each sample station in 

Figure 13.7. The most diverse areas were towards the southern end of the 

export cable corridor, the north-eastern and central parts of Area A and the 

western part of Area B. Areas of markedly lower diversity were at the 

northern end of the export cable corridor, the north-western corner of Area A, 

and the north-eastern part of Area B. 

There was a clear divide across the site with regard to invertebrate diversity. 

At each station; to the east of the Galloper Bank and in the inter and intraarray 

and export cable route areas there were relatively few taxa per station, 

whereas significantly more taxa were recorded to the west of the Galloper 

Bank and across Area A. 

2 

A standard analysis used to calculate species diversity in a community. Diversity indices provide 

more information about community composition than simply species richness (i.e. the number of 

species present); they also take the relative abundances of different species into account. 









Biotopes 

13.4.23 The infaunal assemblages within the study area have been classified using 

the standard marine biotope classification (Connor et al., 2004). Figure 13.8 

(see Page 32) provides an overview of the biotopes found within the GWF 

study area (CMACS, 2010) and a comparison of how they relate to those 

recorded for the GGOWF project in 2005. 

13.4.24 The majority of the GWF site has a good fit with SS.SCS.CCS.MedLumVen 

Mediomastus fragilis, Lumbrineris spp. and venerid bivalves in circalittoral 

coarse sand or gravel and SS.SMX.OMx.PoVen Polychaete-rich deep Venus 

community in offshore mixed sediments which collectively represent the 

‘deep Venus community’ (Figure 13.8). This classification was made on the 

basis of the regular occurrence of species of the polychaete genera 

Lumbrineris and Notomastus and the small burrowing echinoid 

Echinocyamus pusillus in addition to the bivalve diversity from the grab 

samples as a whole (Connor et al., 2004). On a regional scale, MedLumVen 

was the principal biotope at the GGOWF site with a similar dominance of 

Lumbrineris gracilis and Echinocyamus pusillus to the present study 

(CMACS, 2005a). This biotope was also widespread on the London Array 

site (CMACS, 2005b) to the south of the GWF and GGOWF. It is interesting 

to note that the ImoSa biotope (infralittoral mobile sand) biotope that was 

predominant following EIA surveys for GGOWF in 2005 was not identified 

after this survey at the adjacent site. Biotopes are both spatially and 

temporally variable (Connor et al., 2004) and to some extent the gap 

between the surveys is important; however, there are differences in depth 

with more shallow, sandy areas on the Inner Gabbard and Galloper banks 

(GGOWF) amongst a deeper coarse sediment seabed while the GWF area is 

predominantly coarse sediment seabed. Nevertheless, MedLumVen 

dominates the seabed on both wind farm areas as previously described. 

13.4.25 Within the eastern edge of the GWF site boundary, a sandy biotope was 

recorded with a polychaete and amphipod fauna SS.SSA.IFiSa.NcirBat 

‘Nephtys cirrosa and Bathyporeia spp. in infralittoral sand’. Biotopes such as 

these are typical of the southern North Sea and the east coast of England 

with NcirBat recorded at the London Array OWF site (CMACS, 2005) and 

Scroby Sands (Worsfold & Dyer, 2005) with a high abundance of Nephtys 

spp. and Bathyporeia spp. at the Gunfleet OWF site (Titan, 2002, RPS, 2008) 

and Scroby Sands (Worsfold & Dyer, 2005). 

13.4.26 Within the GWF site boundary there were also three discrete patches of the 

coarse sediment with SS.SCS.CCS.PomB. This biotope contained sparse 

infauna but with large numbers of the encrusting polychaete Pomatoceros 

triqueter and the barnacle Verruca stroemia with epifaunal organisms such 

as sea urchins and brittlestars, leading to a classification of 

SS.SCS.CCS.PomB ‘Pomatoceros triqueter with barnacles and bryozoan 

crusts on unstable circalittoral cobbles and pebbles’. This biotope is typical 

of tide-swept conditions where the seabed is unstable; it has not been 

recorded in other wind farm benthic surveys in the southern North Sea but 



the principal species used for the classification, Pomatoceros triqueter, was 

common in samples from the Inner Gabbard and London Array (CMACS 

2005a, 2005b) and Verruca stroemia was abundant in the samples from the 

Inner Gabbard (CMACS 2005a). 

13.4.27 Along the cable corridor three biotopes were recorded: 

� SS.SCS.CCS.PomB; 

� SS.SCS.CCS.MedLumVen; and 

� SS.SSA.IMuSa.SsubNhom 

13.4.28 The inshore portion of the cable corridor was characterized by a sandy 

biotope; which had a fauna of polychaetes and bivalves and was classified as 

SS.SSA.IMuSa.SsubNhom ‘Spisula subtruncata and Nephtys hombergi in 

shallow muddy sand’. Offshore the majority of the cable route was 

dominated by SS.SCS.CCS.PomB with a central portion of MedLumVen. 

13.4.29 A comparison of biotope plots of the adjoining cable routes between GGOWF 

and GWF shows a strong degree of similarity (CMACS, 2010). The surveys 

for the GGOWF cable route in 2005 recorded predominately infralittoral 

mobile clean sand with sparse fauna comprising two subgroups of the 

SS.SSA.IiSa.ImoSa biotope. The difference in faunal composition informing 

the classification may be due to the five year gap between the surveys. 

ImoSa, as present is infralittoral mobile sand and Spisula subtruncata and 

Nephtys hombergii are species adapted to this habitat and therefore the 

SsubNhom classification close to the coast in 2010 is a result of more 

invertebrates in the grab samples than in 2005. 

13.4.30 Outside of the GWF site boundary, two stations at the northern end of the 

survey area were tentatively classified as SS.SSA.CFiSa.EpusOborApri 

‘Echinocyamus pusillus, Ophelia borealis and Abra prismatica in circalittoral 

fine sand’ on the basis of a sparse fauna but with at least one of the principal 

species found in the samples. This biotope is similar to MedLumVen but is 

characterised by finer sediments and has a lower venerid bivalve component. 

It has been widely recorded in the central and southern North Sea (Connor et 

al., 2004). 

13.4.31 There was a single station outside of the GWF boundary to the south-east of 

the wind farm development area where the Ross worm S. spinulosa 

dominated (discussed in more detail in Section 13.4.50) which led to the 

classification of SS.SBR.PoR.SspiMx Sabellaria spinulosa on stable 

circalittoral mixed sediment. S. spinulosa is widespread in sandy areas 

across the southern North Sea and is regularly found in benthic faunal 

samples (e.g. RPS, 2008). This species has been found in sufficient 

abundance to warrant the classification of a separate biotope at several other 

wind farms in the reqion: Inner Gabbard (CMACS, 2005a); Scroby Sands 

(Worsfold & Dyer, 2005) and Thanet (MES, 2005). One of the northerly 

cable route reference stations was also classified as SS.SBR.PoR.SspiMx 

due to the abundance of S. spinulosa. 



13.4.32 The reference station to the south of the cable route comprised coarse 

sediment and the only fauna recorded was the bryozoan Electra pilosa. This 

site was classified as SS.SCS.ICS.SSh Sparse fauna on highly mobile 

sublittoral shingle (cobbles and pebbles), the only occurrence of this biotope 

in the survey. 

13.4.33 In summary the only biotope of potential conservation interest recorded on 

the survey was the S. spinulosa dominated biotope, which was only recorded 

from one station outside of the GWF boundary. For further discussion of S. 

spinulosa see 13.4.49 to 13.4.60. 





Epifauna – regional context 

13.4.34 The MALSF REC project (MALSF, 2009) described epifaunal communities 

largely on the basis of epifaunal species taken from grab samples. The 

project found that none of the epifaunal assemblages across the area 

showed any geographical relationships and tended to correspond with 

coarser gravelly seabed sediment types (MALSF, 2009). With the exception 

of some of the slightly gravelly sand and shell sand substrates, which 

supported assemblages of the hydroid Obelia bidentata together with the 

almost ubiquitous hydroid Sertulariidae (MALSF, 2009), sandy sediments did 

not to support any epifauna. O. bidentata commonly occurs throughout UK 

waters and is typical of sandy sediments attaching to shells (Wilson, 2002). 

Sertulariidae encompass a suite of commonly occurring hydroid species 

found on a variety of surfaces and which can tolerate sediment influences 

such as sand scour (MALSF, 2009). 

13.4.35 The principal epifaunal assemblage, in terms of spatial coverage across the 

Outer Thames Estuary REC, was associated with mixed slightly muddy sand 

and gravel sediments, the surfaces of the larger particles present being 

utilised as attachment sites (MALSF, 2009). The hydroids Sertulariidae are 

consistent components but are rarely associated with any other epifaunal 

species. Where they do occur, sea anemones, Actiniaria and sea squirts 

Molgula manhattensis are found together with the Sertulariidae and form 

discrete sub-types of this assemblage (MALSF, 2009). The other species of 

sea squirt present, Dendrodoa grossularia, formed another small discrete 

assemblage (MALSF, 2009). 

13.4.36 The Port of Felixstowe reconfiguration ES (Posford Haskoning 2003) 

included marine ecological studies that extended to the western boundary of 

the GGOWF area. The epibenthic trawl survey undertaken during the 

reconfiguration EIA recorded the queen scallop Chlamys and pink shrimp 

Pandalus montagui, as well as the polychaete Pomatoceros lamarcki and a 

variety of bryozoan species as being common in the area. Other species 

present in relatively low abundance included, the green urchin P. miliaris the 

hermit crab Pagurus bernhardus and sea star Asterias rubens. Epibenthos 

recorded in the MALSF REC work (MALSF, 2009) included shrimps Crangon 

allmani, C. crangon, P. montagui and Pandalina brevirostris, the brittlestar 

Ophiura albida, gobies Pomatoschistus spp., P. miliaris, and the flying crab 

Liocarcinus holsatus. 

13.4.37 Sabellaria spinulosa is a UK BAP species, and where S. spinulosa forms 

reefs, this is regarded as an Annex I habitat feature under the EU Habitats 

Directive. There are no known occurrences of S. spinulosa forming stable 

reef structure in the proposed development area (MALSF, 2009.), the 

majority of S. spinulosa found within the Outer Thames Estuary REC was 

classified as clumps (i.e. nodules of reef

Epifauna - results of GWF surveys 

Univariate analysis of epifaunal communities 

13.4.38 Analysis of the epibenthic community was carried out on both quantitative 

data (actual abundances) and qualitative data, where presence or absence of 

colonial or encrusting species was recorded. Three site specific surveys 

(autumn 2008, spring 2009 and summer 2010) were undertaken to 

characterise the epibenthic faunal communities associated with the habitats 

present within the GWF site and export cable corridor. Comprehensive 

characterisation of the benthic fish communities is provided in Chapter 14. 

Autumn survey (October 2008) 

13.4.39 A total of eighteen epifaunal trawls were undertaken in October 2008, 

comprising eight within the wind farm site, four within the cable corridor 

routes and six control sites adjacent to the development (Figure 13.9). 

13.4.40 In the analysis of samples obtained from the beam trawl surveys 99 species 

were identified, 23 of which were fish species and 76 invertebrates. The 

results of the beam trawl sampling show that of the quantitative taxa, the 

brittle star Ophiura ophiura was the most abundant accounting for 45% of 

individuals present. Overall, echinoderms represented 54% of individuals 

sampled (Plot 13.3). The next most abundant group were crustacean which 

made up 22% of sampled individuals (Plot 13.3) with the shrimp Crangon 

allmanni representing the most common species in this phylum and 

accounting for 9% of the total catch. Molluscs were the third most abundant 

group (15%) with the bivalve Nucula nitida representing 13% of the total 

individuals sampled. The most abundant annelids were S. spinulosa which 

accounted for 6% of individuals. Species from the gobies (Gobiidae) were 

the most abundant fish species found. 

Spring survey (April 2009) 

13.4.41 A total of eighteen epifaunal trawl routes were undertaken in April 2009, 

comprising eight within the wind farm site, four within the cable corridor 

routes, and six control sites adjacent to the development (Figure 13.1). 

13.4.42 In the analysis of samples obtained from the beam trawl surveys 108 species 

were identified, 24 of which were fish species and 84 invertebrates. The 

brittle star species Ophiura ophiura and Ophiura albida accounted for 25% 

and 18% of the echinoderm group which represented 51% of the total 

individuals recorded (see Plot 13.4). The next most significant group were 

crustaceans (42%) with the most dominant species being the shrimp 

Crangon allmanni which represented 16% of total individuals. The common 

dragonet Callionymus lyra and the lesser sandeel Ammodytes marinus were 

the most abundant fish species in the chordate group. 



Plot 13.3 Proportional representation of the major groups present, based on semiquantitative 

data (October 2008 beam trawls) 

Other 

0% 

Annelida 

7% 

Chordata 

4% 

Mollusca 

15% 

Crustacea 

22% 

Echinodermata 

52% 


data (April 2009 beam trawls) 

Chordata 

3% 

Annelida 

1% 

Other 

1% 

Mollusca 

2% 

Crustacea 

42% 

Spring survey cable route only (March 2010) 

Echinodermata 

51% 

13.4.43 A total of 3,227 individuals from 30 taxa were recorded in the six beam trawls 

along the cable corridor route. 



13.4.44 The most abundant group identified were echinoderms accounting for 95% of 

the species sampled. The dominant species within this group were the brittle 

star Ophiura ophiura which accounted for 86% of individuals sampled. The 

next most abundant group were crustaceans which were dominated by the 

shrimp Crangon allmanni representing 2% of total individuals caught. 


data (cable route only March 2010 beam trawls) 

Mollusca 

0% 

Crustacea 

4% 

Annelida 

0% 

Chordata 

1% 

Ecinodermata 

95% 

Sensitive species and / or habitats 

Ross worm Sabellaria spinulosa 

13.4.45 S. spinulosa is a widespread species common to most sandy sediments of 

the North Sea. It commonly forms aggregations of tightly packed individuals 

living in close proximity and can reach densities of around 4000/m 2 in low 

encrustations of the seabed (Jackson & Hiscock, 2003; Jones et al., 2000). 

13.4.46 This species is included in the UK BAP and, in its biogenic reef form, is 

included as a sub-feature of the Habitats Directive Annex I feature ‘reefs’. 

13.4.47 Encrustations of the species are usually ephemeral in nature, commonly 

forming and disintegrating (Jackson & Hiscock, 2003; Jones et al., 2000) 

through winter storm events and on occasion human activity (such as 

demersal fishing activity (Jones et al., 2000)). The UK BAP for S. spinulosa 

reef notes that “crusts are not considered to constitute true S. spinulosa reef 

habitats because of their ephemeral nature, which does not provide a stable 

biogenic habitat enabling associated species to become established in areas 

where they are otherwise absent”. 

13.4.48 Under certain conditions where dense encrustations develop over time and 

not be subject to disaggregation, the species can form a ‘biogenic reef’. 



Such features are of high ecological importance because of their ability to 

provide complex habitat capable of supporting a number of other organisms 

in what are commonly impoverished environments (i.e. they positively 

contribute to biodiversity and ecosystem function). 

13.4.49 As detailed in Section 13.4.42, S. spinulosa was commonly recorded in 

mainly individual form and on occasion in aggregations, during the GWF 

benthic surveys, but its presence was not evenly distributed. The highest 

abundances were found outside of the revised boundaries of the array area 

(Figures 13.9 and 13.10). The species was also commonly recorded during 

the drop down camera survey of the site; again, the organism’s distribution 

was uneven with the highest abundances generally being found outside the 

revised boundaries. 

13.4.50 At stations where there were high abundances these were often low 

encrusting aggregations on the surface of gravel and larger particles. 

Camera images revealed larger aggregations at three stations (it is noted 

that additional areas from combined grab, camera and sidescan surveys are 

considered below): 

� CG15 (reference station to the north of the export cable route) where 

there were free-standing aggregations approximately 15cm by 10cm in 

area and approximately 15cm high; 

� C54 at the southern end of the eastern part of Area B where there 

were small aggregations on a sandy seabed and a large aggregation 

that almost fills the image but may be S. spinulosa encrusting piddockbored 

rock; and 

� G44 to the east of Area B where there were common low 

encrustations on cobble and boulder with one very large aggregation 

which was not wholly captured in the image but is at least 20cm by 

15cm on its longest axis (height uncertain). 







13.4.51 Of relevance to subsequent assessments of habitat importance is whether 

the findings of S. spinulosa aggregations during the camera survey constitute 

biogenic reef. There are a number of studies which provide guidance on the 

extent of reefiness, including Gubbay, 2007 and Limpenny et al., (2010). 

Feedback from the IPC in the Scoping Opinion recommends the usage of the 

latter study (IPC, 2010). 

13.4.52 The site survey reporting for the GWF benthic work was undertaken prior to 

Limpenny et al., (2010) guidance and therefore used Gubbay, 2007 for 

assessing reefiness of Sabellaria. The following paragraphs have interpreted 

the findings from CMACS, (2010) in light of the Limpenny et al., (2010) 

guidance. 

13.4.53 Using Gubbay (2007) as a guide (relevant at the time of writing), there is a 

possibility that the observations at stations CG15 and G44 (neither of which 

are within the proposed GWF site boundary) constitute ‘low’ reef as the 

aggregations are raised from the seabed and are distributed over a large 

area (hundreds of m 2 ) but overall seabed coverage is low (≤10%). The 

difficulty is that since these areas have not yet been monitored over time, it is 

impossible to tell whether these are fragments of larger aggregations that 

have been dispersed by trawling (trawling scars were apparent in the results 

of the geophysical surveys (Osiris Projects, 2010)) or whether these are new 

aggregations that, if left undisturbed, may become more prominent reef in the 

future. 

13.4.54 It is worth noting that in the images from Station G44, the tops of the larger 

sediment particles have remnants of tubes with a dense coverage of intact 

tubes around the sides of particles. This may be a result of trawl damage or 

could simply be disturbance owing to seabed instability, but regardless of the 

source of damage it is perhaps reasonable to conclude that a stable reef 

structure will not form in the area of G44 as long as the source of disturbance 

remains. 

13.4.55 S. spinulosa is a sessile organism and is vulnerable to disturbance, the 

greatest impact on the species when in reef form is due to physical 

disturbance from fisheries activities 3 . Despite this sensitivity to disturbance, it 

is considered that S. spinulosa has a high recoverability rate following a 

disturbance event owing to the long breeding period, long larval phase and 

relatively rapid initial growth in the first year of settlement of the Sabellaria 

genus (Marine Ecological Surveys (MES), 2007). 

13.5 Assessment of Impacts - Worst Case Definition 

13.5.1 For the purpose of the marine and intertidal ecology impact assessment, the 

worst case scenario, taking into consideration the options currently being 

assessed, is detailed in Table 13.3. 

3 www.ukbap.org.uk 



13.5.2 For this parameter (marine and intertidal ecology) the worst case scenario 

will comprise the design options that provide the maximum area of affected 

seabed 

Table 13.3 Worst case project design for marine and intertidal ecology 

Impact Realistic worst case scenario Justification 

Construction 

Physical 

disturbance of 

intertidal habitat 

Physical 

disturbance of 

subtidal habitat 

Loss of subtidal 

habitat 

Increased 

suspended 

sediments and 

mobilisation of 

Up to 4 rig sites for HDD 100m 2 Provides for the 

maximum amount 

(spatial extent) of 

habitat disturbance. 

Cable installation via plough throughout export 

cable route (5m x 240km = 1.2km 2 ) 

Cable installation via jetting for inter and intraarray 

cables (200km x 5m = 1km 2 ) 

Anchored construction vessels – 4 – 6 anchors 

per vessel (2 – 4m 2 per movement)* 

Jack-up vessel - 6 legs of approximately 10m 2 

per leg. Therefore, 60m 2 in total per 

movement* 

Gravity base structure (GBS) foundations for 

140 WTGs 22,260m 2 

10m of scour protection around each 

foundation 109,900m 2 

3 met mast foundations 116m 2 

Rock placement for cable protection at a total of 

12 export cable crossings 5,400m 2 

Up to 4 ancillary structures (this may comprise 

a combination of offshore substation platforms 

(OSPs), collection platforms and / or 

accommodation platforms) 154m 2 

Provides for the 



habitat disturbance. 




habitat loss. 

As for physical disturbance of subtidal habitat Provides for the 

maximum level of 

seabed disturbance. 




contaminants 

Operation 

Maintenance 

impacts on 

intertidal 

habitats 

Indirect impacts 

on intertidal 

ecology from 

changes in 

current regime 

Maintenance 

impacts on 



on subtidal 

ecology from 

changes in 


Alteration of 



from alteration 

to human 

activities 

Decommissioning 

Impact on 

intertidal 

ecology 


per vessel (2 – 4m 2 )* 



movement* 




N/A See Section 13.7. 


per vessel (2 – 4m 2 per movement)* 



movement* 

Sediment scour at 140 WTGs, worst case 

scenario 16.4m scour pit, depth shallow but 

variable dependent on substrate 




See 13.7.8 – 13.7.13 

As per loss of subtidal habitat Provides for the 



Implementation of 140 x 50m safety zones 

around WTGs and ancillary structures 

N/A See 13.7. 







Impact on 


As for loss of subtidal habitat Provides for the 



*The overall footprint area from these activities will depend on a large number of variables including 

vessel type, layout option and number of movements (influenced by weather and ground conditions). 

13.6 Assessment of Impacts during Construction 

13.6.1 There would be direct and indirect impacts due to construction. Direct 

impacts would be caused by activities that come into contact with the 

benthos (i.e. placement of plant or infrastructure) with indirect impacts 

caused by changes to the physical conditions (i.e. changes in suspended 

sediments or the tidal regime) which may have impacts away from the actual 

construction location. 

Direct impact on intertidal ecology due to physical disturbance 

13.6.2 As discussed in Chapter 6, the export cables would be connected to the 

onshore transition pit through a technique known as horizontal directional 

drilling (HDD) (Chapter 6). HDD is a steerable trenchless method of 

installing underground pipes, conduits and cables in a shallow arc along a 

prescribed bore path by using a surface launched drilling rig, with minimal 

impact on the surrounding area. 

13.6.3 It is expected that up to four rig sites (one for each export cable) for the HDD 

ducts would need to be established on the intertidal at the landfall location, in 

a similar fashion to installation of the cables for the GGOWF. As the exact 

location of the intertidal rig is unknown at this time, for the purposes of the 

assessment, it is assumed that the activity would all take place below 

MHWS. This would comprise ploughing or trenching from low water up to the 

HDD duct where the export cable would be pulled through to the transition 

pit. The footprint of the intertidal rig site would be approximately 25m 2 . The 

rig site and intertidal cable trench would be backfilled upon completion. 

Construction of the rig site and HDD duct would necessitate some vehicular 

access across the intertidal to the site (for example for 20 tonne tracked 360 

degree excavators). 

13.6.4 Impacts on the habitats above MHWS (including the vegetated shingle) are 

discussed in Chapter 24.5, whereas impacts on the habitats below MHWS 

are discussed below. 

13.6.5 The intertidal area within the vicinity of the landfall location is dominated by 

barren littoral shingle .on the upper shore and barren littoral coarse sand on 

the lower shore. The upper shore shingle supports some vegetation and is 

backed by open dune habitat. .With the exclusion of the vegetated shingle, 

the shingle and sand are not known to support any species of conservation 

concern. These habitats are typical in the region and throughout the UK and 

often exposed to high levels of sediment disturbance. Barren sand 



(LS.LSa.MoSa.BarSa) for example, has a very low sensitivity to physical 

disturbance and very high recoverability (Budd, 2008a). The damage to 

marine infauna within the footprint of the rig site would therefore be short 

term as recovery is expected to happen quickly. 

13.6.6 Given the ubiquity and recoverability of the communities present, their low 

sensitivity and the small area of intertidal environment likely to be disturbed 

by cable installation and access routes, it is anticipated that the impacts on 

intertidal ecology would be of negligible significance. 



Table 13.4 Sensitivity of intertidal biotopes identified at the GWF site 

Biotope Definition Value / 

sensitivity 

LS.LCS.Sh.Ba 

rSh 

LS.Lsa.MoSa. 

BarSa 

Barren littoral shingle Low 

Barren or amphipoddominated 

mobile 

sand shores 

LR.FLR.Eph Ephemeral green or 

red seaweed 

communities 

(freshwater or sand- 

Justification* 

(Species traits/recoverability taken from JNCC (2011)) or Marlin – references in 

text) 

Such shores tend to support virtually no macrofauna in their very mobile and 

freely draining substratum. The few individuals that may be found are those 

washed into the habitat by the ebbing tide, including the occasional amphipod 

or small polychaete. 

No macrofaunal life was noted and no species of any sensitivity/value were 

identified 

Not assessed by MarLIN 

Low Most of these shores support a limited range of species, ranging from barren, 

highly mobile sands to more stable clean sands supporting communities of 

isopods, amphipods and a limited range of polychaetes. 

Low 

No macrofaunal life was noted and no species of any sensitivity/value were 

identified 

High recoverability (Budd, 2008a) 

These are biotopes with low species diversity and the relatively high number of 

species in the characterising species list are due to a variation in the species 

composition from site to site, not to high species richness on individual sites. 

Occurrence at 

site 

Dominant 

Dominant 

Present on 

concrete blocks 




sensitivity 

influenced) 

Justification* 

(Species traits/recoverability taken from JNCC (2011)) or Marlin – references in 

text) 

No macrofaunal life was noted in any intertidal biotope, and no species of any 

sensitivity/value were identified 

High recoverability (Budd, 2008b) 

Occurrence at 

site 



Direct impact on subtidal ecology due to physical disturbance 

13.6.7 The installation of cables and other wind farm infrastructure (foundations, 

WTG and ancillary structures) via jack-up barges, anchored vessels, ploughs 

etc would result in the temporary disturbance to the benthos. The 

disturbance would occur within the footprint of the cable installation, beneath 

the legs of the jack-up barges and from the anchors of the construction 

vessels. The final decision on the method of cable installation is still under 

consideration, and the total footprint area disturbed by construction vessels 

would depend on a large number of variables including vessel type, layout 

option and number of movements (influenced by weather and ground 

conditions, techniques and equipment available). Disturbance would take the 

form of displacement of sediment, depressions in the seabed and damage to 

or loss of the communities directly within the footprint of the works (Table 

13.3). 

13.6.8 Subsequently, the area affected cannot be adequately predicted, however 

given a worst case scenario for the intra and inter-array, and export cables 

(Table 13.3) at least 2.2km 2 (approximately 1%) of the total consent 

envelope area of 222km 2 would be affected. 

13.6.9 Whatever, cabling method is chosen; it is likely that the benthos within the 

footprint of the installation would suffer some degree of disturbance during 

installation. However, given the largely ubiquitous nature of the benthic 

communities and their tolerance of disturbance together with the temporary 

nature of the works, any impacts are expected to be minor adverse. 

Monitoring at the Kentish Flats Offshore Wind Farm of similar southern North 

Sea sandy communities has showed no evidence of significant seabed 

change caused by the cable corridor (Emu, 2006). 

13.6.10 Jack-up barges legs could be expected to create depressions in the seabed. 

Following construction, these depressions would be likely to back-fill naturally 

over time. For example, at Kentish Flats the smaller depressions have been 

observed to back-fill by an average of 0.2m over six months in similar types 

of sediments (Emu, 2006). Damage would occur to the infauna within the 

footprint of the jack-up barge legs through compaction of the sediment. 

13.6.11 The majority of the habitat that would be affected across the site comprises 

the deep Venus community. With the exception of S.spinulosa, no species or 

habitats of conservation concern were recorded within the GWF boundaries 

and the infauna present in this region is generally sparse, of low density and 

species richness, and low biomass. Furthermore, the habitats recorded are 

generally widespread throughout the region. Whilst individual species may 

be sensitive to these direct impacts, the effects would be only temporary in 

nature and would be spatially distinct (i.e. the impact would not be repetitive 

at the same location). 



13.6.12 Although S. spinulosa is the most sensitive biotope present at the site, no 

dense aggregations or reefs were recorded within the site boundary (Figure 

13.10). 

13.6.13 Following construction, the habitats and species would be predicted to 

recover. The majority of species and biotopes identified at the site (Table 

13.4) exhibit good potential to recover, particularly to localised and short term 

disturbance of this nature. It is anticipated that the benthic community in the 

area impacted would recover to pre-impact levels and diversity following 

construction, with re-establishment boosted following the subsequent 

spawning and recruitment period to the activity. 

13.6.14 Overall it is considered that this impact would be of minor adverse 

significance, due to the fact that only a small proportion (

Table 13.4 Sensitivity of biotopes identified at the GWF site 


sensitivity 

SS.SCS.CCS. 

MedLumVen 

and 

SS.SMX.OMx. 

PoVen 

SS.SCS.CCS. 

PomB 

SS.SSa.CFiS 

a.EpusOborA 

pri 

“Mediomastus fragilis, 

Lumbrineris spp. and venerid 

bivalves in circalittoral coarse 

sand or gravel” and 

“Polychaete-rich deep Venus 

community in offshore mixed 

sediments” Collectively 

represent the “Deep Venus 

Community” 

‘Pomatoceros triqueter with 

barnacles and bryozoan crusts 

on unstable circalittoral 

cobbles and pebbles’ 

Echinocyamus pusillus, 

Ophelia borealis and Abra 

prismatica in circalittoral fine 

Low to Medium 

Justification 

(Species traits/recoverability taken from MES, 2007) and 

MarLIN (see references) 

The recoverability of Venerid bivalves, depending on the 

species, ranges from low to medium, due to their long life and 

slow growth (Rayment, 2008) 

The polychaete Mediomastus, has a relatively large number 

of eggs and a planktonic larval phase, thus has a medium to 

high recoverability. 

Lumbrineris has a low recoverability due to no larval 

dispersal phase and slow growth 

Negligible Pomatoceros has a long larval phase and early maturation, 

suggesting strong recoverability potential. 

Low 

Barnacles present in this biotope (Balanus sp.) have high 

dispersal and colonisation potential, and thus strong 

recoverability potential (Tyler-Walters, 2008) 

Biotope is similar to MedLumVen (Deep Venus community) 

but is characterised by finer sediments and has a lower 

venerid bivalve component, suggesting a lower sensitivity. 

Occurrence at site 

Dominant, covering the 

majority of the seabed at 

Areas A,B and C 

Outlying stations (some 

areas within the wind farm 

boundary) and a large 

proportion of the cable route 

Northern end of survey area 

(outwith wind farm boundary) 




sensitivity 

SS.SSa.IMuS 

a.SsubNhom 

SS.SSa.IFiSa. 

NcirBat 

SS.SCS.ICS. 

SSh ‘ 

SS.SBR.PoR. 

SspiMx 

sand 

‘Spisula subtruncata and 

Nephtys hombergi in shallow 

muddy sand’ 

‘Nephtys cirrosa and 

Bathyporeia spp. in infralittoral 

sand’. 

Sparse fauna on highly mobile 

sublittoral shingle (cobbles and 

pebbles) 

‘Sabellaria spinulosa on stable 

circalittoral mixed sediment’ 

Justification 

(Species traits/recoverability taken from MES, 2007) and 

MarLIN (see references) 

Negligible This is a sandy biotope with species of strong recoverability 

potential 

Negligible This is a sandy biotope with species of strong recoverability 

potential (Budd, 2008c) 

Occurrence at site 

Inshore portion of cable route 

East side of survey area, 

partly within the wind farm 

boundary 

Negligible Sparse fauna in this biotope suggests negligible sensitivity Reference station to the 

south of cable route 

Medium, except 

where 

considered to be 

biogenic reef, 

where it is of 

high sensitivity 

S. spinulosa contribute to biodiversity and ecosystem 

function by providing a consolidated habitat for epibenthic 

species. Where it forms reefs the value of the resource is 

increased. 

Reefs (including biogenic reefs created by S. spinulosa) are 

listed under Annex I of the Habitats Directive and S. 

spinulosa is a BAP species 

One station to the south east 

of the wind farm boundary, 

and one of the northerly 

cable route reference 

stations (both outwith the 

wind farm boundary) 



Direct impact on subtidal ecology due to the loss of habitat 

13.6.17 The installation of WTG, foundation structures and supporting infrastructure 

would result in long term loss of seabed and associated habitats and fauna 

within the footprint of the structures for the life of the scheme (circa 25 years). 

13.6.18 Using the worst case build scenario detailed in Table 13.3 the maximum loss 

of seabed would be 137,830m 2 (from WTG footprint, scour protection, 

ancillary structures and cable protection materials at cable crossings (see 

Table 13.3 for detail). The majority of seabed lost would be as a result of the 

WTG foundations and associated scour protection. As a worst case, the total 

area affected would constitute 0.08% of seabed within the boundary of the 

GWF site (this percentage uses the total lease area given by The Crown 

Estate of 174.5km 2 , which comprises Development Areas A, B and C. Any 

reduction from the worst case in terms of materials required on the seabed 

would further reduce the area of habitat loss. 

13.6.19 The biotopes present at the site are discussed in Section 13.3. Table 13.4 

summarises these biotopes and assesses their value and sensitivity. 

13.6.20 The majority of the habitat that would be affected consists of a “deep Venus 

community” (SS.SCS.CCS.MedLumVen and SS.SMX.OMx.PoVen). No 

protected or notable species were recorded within this biotope. The biotope 

is not confined to the GWF site boundary, and has also been found outside 

the proposed development area during the benthic survey. At a regional 

scale it appears to be widespread and was found to be the principal biotope 

on the GGOWF site and the London Array site (CMACS, 2010) to the south 

of the GWF and GGOWF sites. 

13.6.21 Of the species and biotopes recorded during the survey, the only one of 

potential conservation concern is S. spinulosa, which was recorded in 

significant numbers at only one site which was located outside the GWF 

boundary. No records of S spinulosa reef were recorded within the study 

area and indeed no dense aggregations were found within the GWF 

boundary (although the latter were recorded outwith the wind farm boundary). 

13.6.22 The majority of the communities that would be affected (such as the deep 

Venus community) are widespread at a regional level and given the worst 

case scenario footprint only a very small proportion of these communities 

would be affected. Furthermore, given the absence of evidence to support 

the presence of any well developed biogenic reef (particularly within the 

study area which might be subject to direct footprint effects), it is considered 

that the GWF would not have a significant impact on S. spinulosa. It is 

therefore considered that the impact on the benthos due to loss of seabed 

would be of minor adverse significance. 

Mitigation and residual impact 

13.6.23 Any pre-construction geophysical and environmental surveys would serve to 

identify any areas of potential S.spinulosa reef habitat that have established 



since baseline surveys. Should any such features be identified then the 

WTG and or ancillary infrastructure foundations and associated scour 

protection will be microsited in order to avoid these features. With these 

mitigation measures in place it is anticipated that the direct impact on the 

benthos would be of negligible significance. 

Indirect impacts on subtidal ecology due to increased suspended sediments 

13.6.24 Sediment disturbance and deposition from construction activities, such as 

cable installation, and foundation laying, could have an adverse indirect 

impact on the benthic communities, due to increased sedimentation in the 

water column resulting in smothering of subtidal organisms. 

13.6.25 The activities which could lead to increased sedimentation would occur 

intermittently for the entire construction period, which is anticipated to take a 

maximum of three years (see Table 6.12 in Chapter 6). 

13.6.26 The levels of anticipated suspended sediments from the construction process 

are detailed in Chapter 10. The seabed sediments across the GWF are 

predominantly sandy gravels with low concentrations of mud. Any fine 

sediment suspended during construction would only be a very small 

proportion (approximately 10%) of the overall sediment on the seabed. The 

majority of the sediment released would be relatively coarse and would most 

likely be re-deposited quickly and in close proximity to the works without 

prolonged suspension. Overall a negligible impact on water quality would 

be anticipated. 

13.6.27 The communities and their associated species, present at the GWF site are 

tolerant of small, localised increases in suspended sediment (Budd, 2008c, 

Tyler-Walters, 2008, Rayment, 2008) as would be expected given the levels 

of natural sediment disturbance at the site. 

13.6.28 Considering the nature of the subtidal environment, and the species present, 

the potential impact of the smothering of subtidal benthos from construction 

activities would be of negligible significance. 

Indirect impacts on subtidal ecology through re-mobilisation of contaminated 

sediments 

13.6.29 Sediment disturbance during the construction phase of the GWF could lead 

to increases in sedimentation and subsequent remobilisation of contaminants 

held within the sediments. An increase in contaminants has the potential to 

impact the benthic communities. 

13.6.30 As discussed in Chapter 11, sediment analysis has indicated that 

contaminant conditions for the area around the GWF are below levels at 

which adverse effects on the benthos are seen, with only elevated levels of 

arsenic detected from sampling. However, elevated levels of arsenic were 

detected at all stations and in one case at a level that is expected to cause 

adverse impacts on the benthos (see Section 11.4). Arsenic is well known 



to occur at elevated levels in the region of the Outer Thames Estuary and 

has been attributed to both historic inputs and geological inputs. 

13.6.31 Only relatively small increases in suspended sediment concentrations are 

predicted during construction which would be localised and of short duration. 

Therefore although there is potential for adverse impacts on the benthos from 

re-mobilised arsenic the level of contaminant released would be a fraction of 

the total suspended sediment and would settle out quickly resulting in a small 

footprint close to the construction works. Therefore, it is anticipated that the 

impact of re-mobilised contaminants on the subtidal benthos would be of 

negligible significance. 

13.7 Assessment of Impacts during Operation 

13.7.1 There would be direct and indirect impacts due to operation. Direct impacts 

would be caused by activities that come into contact with the benthos (i.e. 

placement of plant) with indirect impacts caused by changes to the physical 

conditions (i.e. changes in suspended sediments or the tidal regime) which 

may have imp[acts away from the GWF infrastructure. 

Direct impacts on intertidal ecology due to maintenance activities 

13.7.2 Impacts on the intertidal during operation are considered unlikely as there 

would be no planned maintenance work on the cable. The only potential 

source of impact is therefore, associated with the need to carry out 

emergency maintenance work around the HDD ducts or buried cable down to 

low water. 

13.7.3 No sensitive communities have been identified in the intertidal below MHWS 

at Sizewell; subsequently it is considered that the potential impact on benthic 

communities due to maintenance activities would be of negligible 

significance. 

Indirect impacts on the intertidal ecology due to changes in current regime 

13.7.4 Chapter 10 has identified that there are unlikely to be sources for significant 

impact from the operational phase of the GWF project on coastal processes. 

All export cables will be buried to a minimum depth of 1m although target 

depth is 2m to 3m (see Chapter 6). No potential cable crossings (and 

therefore, cable protection) are indentified within proximity to the coast. 

Given these factors no change on intertidal ecology from exiting conditions 

would be anticipated. 

Direct impacts on subtidal benthos due to maintenance activities 

13.7.5 It may be necessary during the operational phase of the GWF to access the 

buried cables in the subtidal area for unplanned maintenance or repair, which 

could cause localised disturbance to the benthic assemblages directly 

surrounding the cable or WTGs. Maintenance may require the use of jack-up 

barges or anchored vessels depending on the nature of the work and the 

location (see Table 13.3). It is not possible to estimate how many vessel 



movements may be required for maintenance over the operational life of the 

GWF. However, any disturbance would be of limited duration and the best 

practice guidelines will be followed to limit the disturbance. 

13.7.6 It is considered that the potential impact on benthic communities due to 

maintenance activities would be of negligible significance. This is because 

only a very small area of the seabed would be impacted, any disturbance 

would be short-term and sporadic and it is anticipated that the benthos would 

be able to recover relatively quickly from the surrounding area. 

13.7.7 If dense aggregations of S.spinulosa are identified within the GWF site, 

impacts of any maintenance work required in the vicinity of these 

aggregations would be minimised by adhering to best practice and agreeing 

methodologies with the regulators prior to commencement of works. 

Indirect impacts on subtidal ecology due to changes in current regime 

13.7.8 Chapter 10 identifies the worst case scenario with regard to operational 

effects on the hydrodynamic and consequently, sedimentary regime. 

13.7.9 The modelling of predicted changes has yet to be completed. However, 

based on the work carried out by ABPmer on GWF to date (ABP, 2011) and 

drawing upon experience from the adjacent GGOWF project, it is reasonable 

to assume that impacts would be limited to sediment scour within close 

proximity to a small percentage of the foundations. 

13.7.10 This scouring could have a direct and localised impact on the fauna within 

the footprint of the scour. The depth of scour will depend on the physical 

conditions, the thickness of the mobile layer and the cohesiveness of the 

substrate. At the time of writing there are no modelling results for the PER to 

draw on for the GWF site and so the results of predictive studies on similar 

turbine layouts and types at the adjacent GGOWF site are used in this 

assessment. Scour calculations for GBS foundations at locations across the 

GGOWF with different water depths and substrate conditions were calculated 

as part of the GGOWF EIA studies. These predicted scour holes with 

dimensions of 6.5m to 16.2m across, but were limited in depth by the 

presence of only a thin mobile layer (e.g. a veneer of sands and gravels on 

London Clay). On the sandbanks, where the mobile layer is thicker, the 

scour would be greater than sites off the banks. 

13.7.11 The volumes of sediment released through scour at the GGOWF were 

calculated to be double that released during foundation construction (i.e. 

6400m 3 see Section 10.6). It was concluded that the scour phenomena 

would only become significant if the scour holes were to interact with each 

other. The distances between the WTG at the GWF site are large enough 

that this would not occur. 

13.7.12 No sensitive communities have been recorded within the areas of the 

proposed GWF WTGs and the communities are widespread throughout the 

area and the region. 



13.7.13 Any impact would be a long term impact for the life of the scheme (circa 25 

years). Given the small area of seabed affected and the lack of sensitive 

communities it is anticipated that the significance of effects would be likely to 

be negligible at worst, however this will be reviewed once the modelling has 

been completed. 

Direct impact on subtidal benthos due to habitat alteration 

13.7.14 The presence of the WTG and ancillary infrastructure foundations, scour 

protection (where utilised) and cable protection material would change the 

nature of the subtidal habitat. The impacts of the direct loss of the existing 

habitat are assessed as part of the impacts during construction (Section 

13.6). The change would comprise the replacement of natural sedimentary 

seabed with steel piles, concrete foundations and scour protection material. 

13.7.15 Following construction, the new surfaces would be available for colonisation 

by marine fauna. There is considerable literature documenting the 

colonisation of a very wide range of artificial structures at sea (Langhamer et 

al., 2009; Mirto and Danovaro, 2004; Bacchiocchi and Airoldi, 2003 and 

references within GGOWL, 2005). In many cases, such as the Horns Rev 

Offshore Wind Farm in Denmark, colonisation has been rapid, with a diverse 

assemblage of invertebrates present after just 6 months (GGOWL, 2005). 

However, post construction monitoring at Kentish Flats found that the 

communities on monopile foundations were relatively impoverished 

predominantly consisting of the mussel Mytilus edulis (Emu, 2008). 

13.7.16 Even so, some level of colonisation of the foundation structures would occur, 

and could be expected include seaweeds, mussels, barnacles, tubeworms, 

hydroids, sponges, soft corals, amphipods, anemones and other sessile 

invertebrates, as well as more mobile fauna including starfish and crabs 

(Emu, 2008), however the rate and sequence of colonisation is difficult to 

predict. 

13.7.17 Clearly some degree of colonisation by marine organisms would also develop 

on any scour protection, particularly rock based protection. The presence of 

these structures would increase the surface complexity. Complex habitats 

provide a higher surface area for colonisation, protection from predators and 

shelter from stressful conditions such as intense water movement. Richer 

and more diverse communities would therefore be likely in more complex 

structures. 

13.7.18 Encrusting or tube-dwelling animals such as mussels, barnacles, and fouling 

amphipods would be likely to dominate, but a variety of larger mobile 

organisms such as starfish, crabs, prawns, shrimps and small fish could be 

expected, particularly on the parts of the structures and the scour protection. 

13.7.19 Monitoring at Horns Rev indicated that within two years of the completion, the 

monopiles and scour protection were colonised by 11 species of algae and 

65 invertebrate taxa. In addition the mobile invertebrates (decapods and 



molluscs) were found on the scour protection with the sessile species settling 

on the monopiles (Bio/Consult, 2004). 

13.7.20 There is clearly potential for the alteration of habitat at the GWF site to 

improve the productivity of the area through colonisation of the structures 

being placed on the seabed. However, given the localised nature of such 

habitat alteration, and the scale of these changes in relation to the 

communities present in the wider area it is unlikely that the changes would 

result in any significant broadscale community or biodiversity changes. 

Furthermore, given the distances between the structures, and the limited use 

of scour protection material, it is not envisaged that the changes would 

constitute any form of linked reef-like feature. 

13.7.21 Whilst increases in biodiversity could serve as a benefit to the receiving 

environment, in the context of this ES, any change from baseline conditions 

as a result of anthropogenic activity would not be considered to be a 

beneficial impact as it would reduce the “naturalness” of the area. However, 

given the scale of the impact, it is anticipated the impact on the subtidal 

environment due to the alteration of habitat would be of negligible 

significance. 

Indirect impact on subtidal benthos due to alteration to existing human 

activity 

13.7.22 Commercial beam trawling activities currently occurs within the GWF 

boundary, (further detail on fisheries utilising the area is provided in Chapter 

16 Commercial Fisheries). This type of activity can alter habitats leading to 

less diverse habitats dominated by short lived, opportunistic species 

(Jennings and Kaiser, 1998). 

13.7.23 Whilst fishing activity would not be excluded within the GWF site, it is 

possible that trawling activity would reduce due to concerns about health and 

safety with the increased risk of collision with wind farm structures. This may 

have a subsequent impact on the marine benthos. Whilst vessels would be 

able to enter the GWF site during operation, there is potential for 50m 

exclusion zones to be implemented around the WTGs where access would 

not be permitted. Overall, the level of fishing activity would be likely to 

reduce, however this is difficult to quantify due to annual changes in fishing 

activity and quotas. In addition, consultation with some UK based operators 

did not indicate a reluctance to enter the GWF site once operational, however 

there are concerns surrounding health and safety and insurance costs (for a 

detailed assessment of implications for commercial fisheries see Chapter 

16). 

13.7.24 This reduction in fishing activity could aid in the recovery of areas and the 

development of habitats of higher diversity and complexity. However, due to 

the uncertainties surrounding the change in fishing activity, the potential for a 

positive impact upon benthic ecology cannot be confirmed at this stage. It is 

anticipated that the subsequent impact on the subtidal would be of negligible 

significance. 



13.8 Impacts during Decommissioning 

13.8.1 There would be the potential for impacts due to the removal of GWF 

infrastructure. 

Impact on intertidal ecology 

13.8.2 During decommissioning it is anticipated that export cables would be cut at 

the grade point and therefore the intertidal communities where the cable is 

situated are unlikely to be disturbed. Therefore, it is anticipated that there 

would be no change to the intertidal ecology during the decommissioning 

phase. 

Impact on subtidal ecology 

13.8.3 It has been assumed that decommissioning would include the removal of all 

offshore structures, GBS foundations would be fully removed and piled 

foundations would be cut off at or just below the seabed. The removal of the 

infrastructure would necessitate the use of a heavy lift vessel. Intra-array 

and export cables would be expected to be cut at the grade in point of burial 

protection and left in situ. 

13.8.4 Impacts would be similar to those described for the construction phase 

(physical disturbance, loss of habitat, smothering and re-mobilisation of 

contaminants), although these would be significantly lower in magnitude. 

13.8.5 There is potential that sensitive features (such as S.spinulosa reef) not 

currently present may develop within the area during the operational period. 

From a precautionary standpoint, therefore, there may be minor adverse 

impacts during the decommissioning phase. 

Mitigation and residual impact 

13.8.6 It is anticipated that surveying of the benthic community could be a 

requirement of the pre-decommissioning environmental surveys (Chapter 31 

Outline Environmental Mitigation and Monitoring Plan). Should any such 

surveys show that the benthic assemblages had developed to such an extent 

that the decommissioning process would result in unacceptable levels of 

impact, then GWFL would look to agree a modification to the 

Decommissioning Plan that allows some structures to remain on the seabed, 

where considered acceptable on HSE grounds. Subsequently, in light of 

such mitigation measures the residual impact on the subtidal benthos from 

decommissioning would be of negligible significance. 

13.9 Inter-relationships 

13.9.1 The inter-relationships between the marine and intertidal ecology and other 

physical, environmental and human parameters are inherently considered 

throughout the assessment of impacts (Sections 13.6 and 13.7). Table 13.5 

summaries those inter-relationships that are considered of relevance to the 



intertidal and subtidal benthic communities and, identifies where within the 

ES these relationships have been considered. 

Table 13.5 Marine and intertidal ecology inter-relationships 

Inter-relationship Section where addressed Linked Chapter 

Influence of effects on 

physical processes 

Influence of changes in 

human activity 

Influence of changes in 

water quality 

Section 13.3 paragraph 

13.3.22 


13.6.26 


13.7.4 

Section 13.7 paragraphs 

13.7.22 and 13.6.23 


13.6.30 

Chapter 10 Physical 

environment 

Chapter 16 Commercial 

fisheries 

Chapter 11 Marine and 

Coastal Water Quality 

13.9.2 Chapter 29 Inter-relationships provides a holistic overview of the interrelated 

impacts that have the potential to manifest on intertidal and benthic 

receptors over all development phases of the GWF project. 

13.10 Cumulative Impacts 

13.10.1 The unmitigated impacts identified during the construction (Section 13.6) 

operation (Section 13.7) and decommissioning phases (Section 13.8) of the 

GWF project that could result in cumulative impacts comprise: 

� Loss of subtidal habitat; 

� Physical disturbance from construction vessels and cable installation; 

� Indirect impacts due to increases suspended sediment; 

� Indirect impacts through change in current regime; 

� Direct impacts on benthos due to maintenance activities; 

� Direct impact on subtidal benthos due to habitat alteration; and 

� Indirect impact on subtidal benthos due to alteration to existing human 

activity. 

13.10.2 Cumulative impacts associated with the GWF project could occur on a 

number of levels: 

� Interactions between different aspects of the GWF project with other 

wind farms; and 



� Interactions with other activities occurring in the region. 

13.10.3 The following paragraphs provide an assessment of the potential for 

cumulative impact over these varying levels. 

GWF and other wind farms 

13.10.4 The adjacent GGOWF project would impact the subtidal and intertidal 

environment, which share similar and linked communities to those found at 

GWF. 

13.10.5 There would be no overlap of construction activity with GWF and GGOWF 

and as no operational impacts would be predicted from GGOWF on the 

intertidal there are no potential pathways for cumulative impacts to occur 

within the intertidal environment. 

13.10.6 With regard to the long term loss of seabed in the footprint of the wind farm 

structures, the GGOWF ES (GGOWF, 2005) predicted, as a worst case 

scenario, that a total of 0.225% of seabed within the GGOWF project 

boundary would be lost. When this is added to the predicted losses of the 

GWF project (0.08%), the total percentage loss over both sites would be 

approximately 0.3% of the total area represented by the two projects. This 

small scale loss in relation to the habitats and communities that are present 

is unlikely to result in impacts that are cumulatively any more significant than 

those which are predicted for the GWF alone. Furthermore, the GGOWF 

percentage is based on GBS foundations (as a worst case within the ES) 

rather than the as built monopile foundations. 

13.10.7 With regard to the impacts associated with construction activity of the other 

offshore wind farms in the Outer Thames Estuary, there would be potential 

for an overlap of activity with the second phase of the London Array and the 

first phase of the Zone 5 Round 3 project which is being developed by East 

Anglia Offshore Wind (EAOW), known as East Anglia ONE. This assumption 

is based upon the currently planned construction schedules for these 

projects. 

13.10.8 With regard to London Array, given the distance between the two projects 

(~16km) it is considered that would not be any pathways for indirect 

cumulative effects (given the findings presented in Sections 13.6 and 13.7 

above) on the benthos and, therefore no cumulative impacts are predicted. 

13.10.9 Although the timeline of East Anglia ONE is, at this stage, subject to change, 

commencement of offshore construction works are anticipated to begin in 

2015. Preliminary plans show that the broad corridor within which the East 

Anglia ONE export cable is likely to be located begins to the north of GWF, 

crosses the GWF cable route and reaches landfall around Ipswich, and the 

ports of Harwich and Felixstowe (East Anglia Offshore Wind, 2010). 

Therefore there is potential for both spatial and temporal overlaps in 

construction as construction of the GWF would begin during 2015 (see 



Chapter 6 Project Details). However, it is likely that all major construction 

(i.e. piling and cable laying) would have already been completed at GWF 

prior to the start of East Anglia ONE project, and those impacts identified for 

GWF would be highly localised and short term. Given the timescales, and 

the nature of the predicted impacts, no cumulative impacts are anticipated. 

13.10.10 With regard to direct impact on subtidal habitats from construction activities 

(installation of infrastructure and cables) the impacts, would be highly 

localised. In addition, the only sensitive habitat in the region (Sabellaria 

spinulosa reef) either does not occur or be avoided by micro-siting of 

infrastructure and best practice minimizing plant movements. Any 

disturbance of the habitats would also be temporary, restricted to the period 

of construction activity. Given that the impact from GWF would be negligible 

and other wind farms would also undertake similar mitigation during the 

construction phase there would be no pathway for significant cumulative 

impact. 

13.10.11 With regard to direct impacts from maintenance activities, these would be 

restricted to the areas in the immediate vicinity of the works for routine 

maintenance; impacts would be highly localised and temporary. By following 

best practice impacts would be further minimised. At this juncture it is not 

possible to predict the scale of maintenance works required for GWF or 

indeed other sites, however given that these would be highly localised and 

temporary it is unlikely that the cumulative impact across sites at the regional 

scale would be significant. 

13.10.12 It is expected that direct impacts due to habitat alteration (i.e. development of 

fouling communities on the hard substrate provided by infrastructure) would 

again be highly localised to the WTGs and any scour protection. For GWF it 

is considered that this impact would be negligible and there would not be a 

true ‘reef’ created due to the distances between WTGs. Across wind farms 

the same would hold true, the area of habitat change within the wider region 

would be negligible and there would not be a significant cumulative impact. 

13.10.13 Indirect impacts to the benthos due to alteration in human activities are 

confined to any changes of fishing pressure due to the presence of the wind 

farms. No wind farms are currently entirely closed to fishing so it is likely that 

if compatible fishing activities (i.e. those utilizing static gear) currently occur 

within a site these would continue. It is not possible at this juncture to 

determine what level of decrease in fishing activity may occur and what the 

subsequent indirect impact on the benthos would be, especially considering 

concurrent decreases in fishing capacity and potential for quota changes. 

However, given the area of the wind farms compared to the wider available 

area for fishing and the widespread nature of the communities across the 

region it is unlikely that there would be a significant cumulative impact due 

any reduction in fishing effort. 

13.10.14 As detailed in Section 13.7 (and supported by the outcome of hydrodynamic 

modelling reported in Chapter 9) indirect construction and operational 



impacts would be localised to the immediate vicinity of the project. Potential 

pathways for indirect operational impacts between the GWF project and other 

wind farm developments do not exist. 

GWF and other activities 

13.10.15 There are limited additional human activities occurring within the vicinity of 

the GWF project site, with the exception of aggregate extraction, which is 

discussed in more detail in Chapter 19 Other Human Activity. Given the 

extent and duration of impacts from GWF and the distance to other seabed 

activities, and the common and widespread nature of species and habitats, 

the potential for significant cumulative impacts is considered unlikely. 

13.10.16 Further consultation with the aggregate industry during the EIA will establish 

the status of the extraction application and prospecting areas (notably Areas 

498 and 407 – see Chapter 19). Should any activities be identified which 

would be concurrent with construction at GWF then there is potential for 

cumulative impacts, and these will be included within the EIA. 

13.10.17 Sizewell Power Station has a number of existing marine components, 

comprising inlet and outlet pipes for both Sizewell A and Sizewell B (see 

Chapter 19). There are localised thermal plumes associated with the outlet 

pipes, however, their impact footprint would not overlap with that of the GWF 

cable works and therefore, potential for cumulative impact is considered 

unlikely. Sizewell also has expansion plans, although a formal Scoping 

Report for Sizewell C has not yet been submitted. . This development, if it 

were to go ahead, would likely be to the north of the existing Sizewell 

infrastructure. Given the limited marine works (installation of inlet and outlet 

pipes, the distance between the development and GWF the potential for 

cumulative impact on either the intertidal and or marine ecology is considered 

limited. 

13.11 Outline Monitoring 

13.11.1 It is possible that monitoring of the GWF site would be carried out in order to 

verify predicted impacts on the benthic environment. Based on the level of 

monitoring required for GGOWF, pre and post construction monitoring at 

GWF may comprise annual sampling for up to three years, or until the 

predictions made in the GWF ES can be verified as not having a significant 

impact on the receiving environment. Typically, such monitoring techniques 

may comprise: 

� Replicate grab sampling / drop down camera on a predetermined grid 

for benthic organisms; 

� Beam trawls at predetermined locations for epi-benthic organisms; 

and 

� Monitoring of the colonisation of monopiles - determined by video 

observations and analysis with some accompanying sample collection 

for verification and identification. 



13.11.2 GWFL, however, do not necessarily assume that as monitoring was required 

at GGOWF, that it will be carried out to the same extent or even an automatic 

necessity at GWF. Given the knowledge built up by monitoring at GGOWF 

and the lack of significant impacts anticipated, GWFL would look to ensure 

that any monitoring is proportionate. The detail of which will be discussed in 

more detail with the relevant stakeholders (MMO, JNCC, Natural England 

and Cefas) as the project progresses. 

13.12 Summary 

13.12.1 This Chapter of the PER has provided a characterisation of the existing 

marine and intertidal environment based on both existing and site specific 

survey data, which has established that communities present are indicative of 

the region and occur over broad extents throughout the Outer Thames 

Estuary and southern North Sea. Species of conservation importance (such 

as S.spinulosa, have been recorded within the study area, although none 

found in their most sensitive and important form (biogenic reef). 

13.12.2 Table 13.6 provides a summary of the predicted impact on marine and 

intertidal ecology. 

Table 13.6 Summary of impacts 

Description of 

Impact 

Construction Phase - Intertidal 

Direct impact due 

to physical 

disturbance 

Construction Phase - Subtidal 


to physical 

disturbance on 

subtidal ecology 


to loss of habitat 

Indirect impact due 

to increased 

Impact Potential Mitigation Measure Residual impact 

Negligible N/A N/A 

Minor 

adverse 

Minor 

adverse 

Jack up barge movements kept to 

a minimum. 

Micrositing of equipment/cables if 

any areas of S. spinulosa reefs 

are identified. 

Micrositing of turbines, cables and 

associated infrastructure if any 

areas of S. spinulosa reefs are 

identified 


Negligible 

Negligible 




Impact 

suspended 

sediments 


to re-mobilisation of 

contaminated 

sediments 


Negligible 

Operation Phase - Intertidal 

Direct impacts due 

to maintenance 

activities 


to changes in 


Negligible 

Operation Phase - Subtidal 


to maintenance 

activities 


to changes in 


Indirect impact 

through habitat 

alteration 

Indirect impact 

through alteration 

to existing human 

activity 

No change 

Negligible 

Negligible 

Negligible 

Negligible 

Decommissioning – Intertidal 

Impact on ecology No change 

Decommissioning – Subtidal 


to physical 

Minor 

adverse 

N/A N/A 

N/A N/A 

N/A N/A 

Best practice followed to minimise 

any impacts 


Final Report Chapter 13 - Page 57 3 June 2011 

N/A 

N/A N/A 

N/A N/A 

N/A N/A 

N/A N/A 

Jack up barge movements kept to 

a minimum. 

Negligible


Impact 

disturbance on 

subtidal ecology 


to loss of habitat 


to increased 

suspended 

sediments 


to re-mobilisation of 

contaminated 

sediments 


Minor 

adverse 

Micrositing of equipment if any 

areas of S. spinulosa reefs are 

identified. 

Should surveys show that benthic 

assemblages have developed to 

such an extent that the 

decommissioning process would 

result in unacceptable levels of 

impact, then GWFL will explore 

the potential for a 

Decommissioning Plan that allows 

some structures to remain on the 

seabed. 



Negligible 

13.12.3 No significant impacts would be anticipated over the construction, operation 

or decommissioning phases of GWF on the intertidal or subtidal environment. 

13.12.4 GWFL would look to ensure that the nature of any monitoring would be 

proportionate to the impacts predicted and any such monitoring requirements 

will be defined through further consultation with the relevant stakeholders. 



13.13 References 

ABPmer, (2011). The Galloper Wind Farm: Assessment of Rochdale 

Envelope Conditions with Respect to Baseline Tide and Wave Conditions. 

ABPmer Report R.1791TN, April 2011 

Bacchiocchi, F and Airoldi, L. (2003). Distribution and dynamics of epibiota 

on hard tructures for coastal protection. Estuarine, Coastal and Shelf Science 

56 (2003) 1157–1166 

Barne, J.H., Robson, C.F., Kaznowska, S.S., Doody, J.P., Davidson, N.C. 

and Buck, A.L., eds. (1998). Coasts and seas of the United Kingdom. Region 

7 South-east England: Lowestoft to Dungeness. Joint Nature Conservation 

Committee, Peterborough (Coastal Directories Series). 

Bio/Consult (2004). Hard Bottom Substrate Monitoring Horns Rev Offshore 

Wind Farm Annual Status Report 2003. Report to Elsam Engineering Ltd, 

published May 2004 

Boyd, S. E. (compiled, 2002). Guidelines for the conduct of benthic studies at 

aggregate extraction sites. London: Department for Transport, Local 

Government and the Regions, 117pp. 

Brown and May Marine Ltd (2009a). Greater Gabbard Wind Farm Extension. 

Pre construction fish survey, Spring 2009 

Brown and May Marine Ltd (2009b). Greater Gabbard Wind Farm Extension. 

Pre construction fish survey, Autumn/Winter 2008 

Budd, G.C. (2008a). Barren coarse sand shores. Marine Life Information 

Network: Biology and Sensitivity Key Information Sub-programme [on-line]. 

Plymouth: Marine Biological Association of the United Kingdom. [cited 

22/03/2011]. Available from: 

 

Budd, G.C. (2008b) Ulva spp. on freshwater-influenced or unstable upper 

eulittoral rock Marine Life Information Network: Biology and Sensitivity Key 

Information Sub-programme [on-line]. Plymouth: Marine Biological 

Association of the United Kingdom. [cited 22/03/2011]. Available from: 

http://www.marlin.ac.uk/habitatsensitivity.php?habitatid=104&code=2004 

Budd, G.C. (2008c). Nephtys cirrosa and Bathyporeia spp. in infralittoral 

sand. Marine Life Information Network: Biology and Sensitivity Key 

Information Sub-programme [on-line]. Plymouth: Marine Biological 

Association of the United Kingdom. [cited 07/05/2011]. Available from: 

 



Centre for Environment, Fisheries and Aquaculture Science (Cefas) (1997). 

Monitoring and Surveillance of Non-radioactive Contaminants in the Aquatic 

Environment and Activities Regulating the Disposal of Wastes at Sea, 1994. 

Aquatic Environment Monitoring Report No 47, Centre for Environment, 

Fisheries and Aquaculture Science, Lowestoft. 


Offshore Wind Farms Guidance note for Environmental Impact Assessment 

in respect of FEPA and CPA requirements, Version 2, June 2004. 


Draft guidelines for data acquisition to support marine environmental 

assessments for offshore renewable energy projects 

Centre for Marine and Coastal Studies (CMACS), (2005a). Greater Gabbard 

Offshore Wind Farm Environmental Impact Assessment. Benthic Ecology 

Technical Report. 

Centre for Marine and Coastal Studies (CMACS), (2005b). London Array 

Environmental Impact Assessment. Benthic Ecology Technical Report. 

Centre for Marine and Coastal Studies (CMACS), (2010). Galloper Offshore 

Wind Farm. Benthic Survey Technical Report 2010. Prepared for OSIRIS 

PROJECTS (NRL and SSER). Included within Appendix X. 

Connor, D.W, Allen, J.H, Golding, N, Howell,K.I, Lieberknecht, L.M, Northern 

N and Reker, J.B, (2004). The Marine Habitat Classification for Britain and 

Ireland Version 04.05. JNCC, Peterborough ISBN 1 861 07561 8 (internet 

version). Available at URL: www.jncc.gov.uk/MarineHabitatClassification. 

Accessed 15 March 2011 

Department of Energy and Climate Change (DECC), (2009). Revised Draft 

National Policy Statement for Renewable Energy Infrastructure (EN-3), 

Dudgeon Offshore Wind Limited, (2009). Dudgeon Offshore Wind Farm – 

Environmental Scoping Study. Produced for Dudgeon Offshore Wind Limited. 

East Anglia Offshore Wind, (2010). East Anglia ONE offshore wind farm. EIA 

Scoping Report. Supplementary information on connection to the onshore 

electricity network 

Emu, (2006). Kentish flats Offshore Windfarm Post-Construction Swath 

Survey 3. Report No. 06/J/1/0942/0590 to Kentish Flats Limited 

Emu, (2008). Kentish Flats Offshore Wind Farm Turbine Foundation Faunal 

Colonisation Diving Survey. Report No 08/J/1/03/1034/0839 Final November 

2008. 



Frauenheim, K., Neumann, V., Theil, H. & Türkay, M. (1989). The distribution 

of larger epifauna during summer and winter in the North Sea and its 

suitability for environmental monitoring. Senckenbergiana maritima, 20(3/4): 

101-118. 

GE Wind Energy, (2002). Gunfleet Sands Offshore Wind Farm 

Environmental Statement. Prepared by Hydrosearch Group, copyright GE 

Gunfleet Ltd. 

Glemarec, M. (1973). The benthic communities of the European North 

Atlantic continental shelf. Oceanography and Marine Biology, Annual Review, 

11: 263-289. 

Greater Gabbard Offshore Wind Limited (GGOWL), (2005). Greater Gabbard 

Offshore Wind Farm Environmental Statement, October 2005 

GREP, (2002). Kentish Flats Offshore Wind Farm Environmental Statement. 

Prepared by Emu Ltd on behalf of Global Renewable Energy Partners. 

Gubbay S, (2007). Defining and managing Sabellaria spinulosa reefs: report 

of an inter-agency workshop 1-2 May, 2007. Joint Nature Conservation 

Committee Report No. 405. 22pp. JNCC, Peterborough. ISSN 0963-8091. 

Hiscock, K, Tyler-Walters, H. and Jones, H. (2002). High level Environmental 

Screening Study for Offshore Wind Farm Developments – Marine Habitat 

and Species Project. Report from The Marine Biological Association to The 

Department of Trade and Industry New & Renewable Energy Programme. 

(AEA Technology, Environmental Contract: W/35/00632/00/00.) 

IPC, (2010). Scoping Opinion, Proposed Galloper Wind Farm Project. August 

2010 

Jackson, A and Hiscock, K (2008). Sabellaria spinulosa. Ross worm. Marine 

Life Information Network: Biology and Sensitivity Key Information Subprogramme 

[on-line]. Plymouth: Marine Biological Association of the United 

Kingdom. [cited 29/03/2011]. Available from: 

 

Jennings S., Kaiser M. J. (1998). The effects of fishing on marine 

ecosystems. Advances in Marine Biology;34:201-352. 

Joint Nature Conservation Committee (JNCC) (2011) Marine Habitat 

Classification Hierarchy [cited 29/03/2011]. Available from: http://jncc 

.defra.gov.uk/marine/biotopes/hierarchy.aspx 

Jones, L.A, Coyle, M.D, Evans, D, Gilliland, P.M and Murray, A.R. (2004). 

Southern North Sea Marine Natural Area Profile: A contribution to regional 

planning and management of the seas around England. Peterborough, 

English Nature. 



Jones, L.A., Hiscock, K., and Connor, D.W. (2000). Marine habitat reviews. A 

summary of ecological requirements and sensitivity characteristics for the 

conservation and management of marine SACs. Joint Nature Conservation 

Committee, Peterborough. (UK Marine SACs Project report). 

Kunitzer, A., Basford, D., Craeymeersch, J.A., Dewarumez, J.M., Dorjes, J., 

Duineveld, G.C.A., Elefttheriou, A., Heip, C., Herman, P., Kingston, P., 

Niermann, U., Rachor, E., Rumohr, H., and de Wilde. P.A.J. (1992). The 

benthic infauna of the North Sea: species distribution and assemblages. 

Journal of Marine Science. 49 pp:127-143. 

Langhamer, O., Wilhelmsson, D., Engstrom, J., (2009). Artificial reef effect 

and fouling impacts on offshore wave power foundations and buoys – a pilot 

study. Estuarine, Coastal and Shelf Science 82 (2009) 426–432 

Limpenny, D.S., Foster-Smith, R.L., Edwards, T.M., Hendrick, V.J., Diesing, 

M., Eggleton, J.D., Meadows, W.J., Crutchfield, Z., Pfeifer, S. and Reach, 

I.S., (2010). Best methods for identifying and evaluating Sabellaria spinulosa 

and cobble reef. Natural England, Supported through Defras Aggregates 

Levy Sustainability Fund 

London Array Limited (LAL), (2005). London Array Offshore Wind Farm 

Environmental Statement. RPS plc. 

Marine Aggregate Levy Sustainability Fund (MALSF), (2009). Outer Thames 

Estuary Regional Environmental Characterisation 

Marine Ecological Surveys Limited, (2005). Thanet Offshore Wind Farm 

Benthic & Intertidal Resource Survey. 

Marine Ecological Surveys Limited, (2007). Predictive framework for 

assessment of recoverability of marine benthic communities following 

cessation of aggregate dredging. Technical Report to the Centre for 

Environment, Fisheries and Aquaculture Science (CEFAS) and the 

Department for Environment, Food and Rural Affairs (Defra). Project No 

MEPF 04/02. Marine Ecological Surveys Limited, 24a Monmouth Place, 

Bath, BA1 2AY. 

Mirto, S. and Danovaro, R, (2004). Meiofaunal colonisation on artificial 

substrates: a tool for biomonitoring the environmental quality on coastal 

marine systems. Marine Pollution Bulletin 48 (2004) 919–926 

Osiris Projects. (2010). Areas A, B, C, D, R1 & R2 Geophysical and Benthic 

Ecology Survey Volume 2a – Areas A, B, C, R1 and R2 REPORT C9028 

(May 2010) 

Posford Haskoning. (2003). Felixstowe South Reconfiguration Environmental 

Statement; Subtidal Marine Communities. 



Rayment, W.J. (2008). Venerid bivalves in circalittoral coarse sand or gravel. 

Marine Life Information Network: Biology and Sensitivity Key Information 

Sub-programme [on-line]. Plymouth: Marine Biological Association of the 

United Kingdom. [cited 07/05/2011]. Available from: 

 

RPS. (2008). Preconstruction Benthic Ecology. Gunfleet Sands Offshore 

Wind Farm Development. A report to Gunfleet Sands Ltd. 

SSER and RWE NRL, (2010). Galloper Wind Farm Project Scoping Study. 

Client: SSE Renewable Developments UK Ltd and RWE Npower Renewable 

Ltd 

Tyler-Walters, H. (2008). Pomatoceros triqueter, Balanus crenatus and 

bryozoan crusts on mobile circalittoral cobbles and pebbles. Marine Life 

Information Network: Biology and Sensitivity Key Information Subprogramme 

[on-line]. Plymouth: Marine Biological Association of the United 

Kingdom. [cited 07/05/2011]. Available from: 

 

Wilson, E. (2002). Obelia bidentata. A hydroid. Marine Life Information 

Network: Biology and Sensitivity Key Information Sub-programme [on-line]. 

Plymouth: Marine Biological Association of the United Kingdom. [cited 

29/03/2011]. Available from: 

 

Worsfold, T.M. & Dyer, M.F. (2005). Benthic Ecology of Scroby Sands 

windfarm site: results of July 2005 (post-construction) survey and comparison 

with 1998 (pre-construction) survey. Unicomarine Report EONSCR05 to 

E.ON UK Renewables Offshore Wind Ltd, October, 2005.

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